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Phobos
The two small moons of Mars, Phobos and Deimos, are easy targets for spaceships. Requirements Both moons have very little gravity, which makes landing and liftoff very easy. Also, both moons offer unique challenges. There was an attempt to land on Phobos, that failed because of its low gravity. Also, the European Space Agency (or ESA for short)'s Rosetta ''probe and the lander, ''Philae, experienced problems because its target (a comet), has a gravity that is too weak for the lander to stay put on it. A mission to Phobos and Deimos requires a vehicle able to reach Mars orbit and is easier to conduct then a mission to Mars. Both moons lack any atmosphere, so parachutes are useless. Also, because of their small gravity, landing legs might not be needed. Rovers might find very difficult to navigate on the surface, given the very low gravity (and might end-up in orbital or suborbital trajectories). A more efficient way to explore the moons is to use RCS thrusters. Both moons have irregular shapes and small spheres of influence and thus cannot be used for Gravity assists. However, flying between them is possible with very little fuel. A return vehicle could return to Earth with very little fuel left. Exploration Basically, any space mission to Mars have the opportunity to explore the moons, because of their proximity. Even Mars rovers did return images of the moons, including eclipses. Flyby Sometimes, a ship en route to Mars can come very close to one of the moons, even entering its Sphere of Influence, without the intention to do so. A close flyby, crossing the Sphere of Influence, is possible with some trajectory adjustments. Orbit In reality, orbits around Phobos and Deimos are not safe, because both moons have irregular shapes and gravitational strength is not even. However, in the simulator, orbits are stable. In order to get into orbit, a ship needs to fire its engines with a really low amount of thrust. One second of a full engine burn can send a ship out of the moon's sphere of influence. Engines must be operated at low thrust (below 10%). A ship can deorbit very easy, by firing its engines for a few seconds. Landing Landing on the moons is very easy. The ship must decelerate enough, then wait while it descends and lands. Small and short engine burns might be needed to slow down. The use of RCS Thrusters might be required. A very interesting fact is that a ship needs to touch the surface only with one part. Due to the small gravity, it takes a lot of time for the ship to fully touch the surface. The ship might eventually turn over. However, because of the low gravity, by firing an engine very slowly, a ship can lift off even from difficult positions. Advanced Missions It is possible to do far more than just a short visit. Advanced Rovers Driving Rovers on Phobos or Deimos is very hard. Vehicles will turn over and might even go into orbit. A different strategy is needed. A much more efficient vehicle needs propulsion. For example, a small probe, with RCS Thrusters or Ion Engines, will work far better. Mars Space Station Many scientists and sci-fi writers proposed that Phobos should become a space base for Mars exploration. Because of its low gravity, it is far more easy to land on, merge ships, refuel and make a stock of resources. A Phobos or Deimos base can host ships able to land on Mars or return to Earth. Phobos has more space to work on. See Also *What To Do In Spaceflight Simulator *Mars Activities Category:Activities Category:Tutorial